Apparatus and method for manufacturing three-dimensional netted structure

ABSTRACT

An apparatus for manufacturing a three-dimensional netted structure, the three-dimensional netted structure including a plurality of filaments of resin, the filaments being helically and randomly entangled and thermally bonded together, the apparatus including: an extrusion molding machine including a plurality of dies each having a mouthpiece with a plurality of holes; a pair of endless conveyors provided with endless members; a motor adapted to drive the endless members; and a tank adapted to partly submerge the endless conveyors therein. A method of manufacturing a three-dimensional netted structure using the apparatus by extruding molten filaments of a thermoplastic resin downward from the dies via the mouthpiece, helically entangling the molten filaments by entangling actions of the endless members, and cooling the entangled filaments in a liquid in the tank.

CROSS-REFERENCE TO RELATED APPLICATIONS

This Application is a continuation of U.S. application Ser. No.12/497,567, filed Jul. 3, 2009, now pending, which is a continuation inpart of U.S. Application Ser. No. 10/221,568, which is a National StageAppl. filed under 35 USC 371 of Int'l Pat. Appl. No. PCT/JP2001/002046filed on Mar. 15, 2001, now abandoned, and claims priority benefits toJapanese Pat. Appl. Nos. 2000-072977 filed Mar. 15, 2000, 2000-279721filed Sep. 14, 2000, 2000-279792 filed Sep. 14, 2000, 2000-281309 filedSep. 18, 2000, 2000-281319 filed Sep. 18, 2000, 2000-281329 filed Sep.18, 2000, 2000-281341 filed Sep. 18, 2000, and 2000-285855 filed Sep.20, 2000. The contents of all of these applications, including anyintervening amendments thereto, are incorporated herein by reference intheir entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a three-dimensional netted structure used fora cushioning material and the like, and a method of and an apparatus formanufacturing the same.

2. Brief Description of the Related Arts

Known methods of manufacturing a void-carrying three-dimensional nettedstructure include a method disclosed in Japanese Pat. Publ. KOKOKU No.S50-39185, or a method disclosed in Japanese Pat. Laid-Open KOKAI No.S60-11352, etc., which is adapted to manufacture resin cotton on whichpolyester fibers are bonded with a bonding agent made of, for example, arubber-based material. There are also methods of or apparatuses formanufacturing a void-carrying three-dimensional netted structure byentangling resin threads by endless belts, and such methods orapparatuses include the invention disclosed in Japanese Pat. Laid-OpenKOKAI No. H11-241264, etc.

However, the demands for a product of such a three-dimensional nettedstructure have been diversified. It is necessary that each of nettedstructures manufactured be finished to one of different shapes bycutting or molding the netted structures to demanded shapes in a laterstage of the manufacturing stage. This causes a product finishingoperation to become very complicated.

A three-dimensional netted structure manufactured by a prior art methodbecomes low in density in some cases. Since both surface portions of abundle contact belt conveyors, outer surfaces of the bundle aresubstantially flattened. However, left and right end surfaces of thebundle have an irregular, helical shape, and side surfaces thereof havea laterally wavy non-straight shape.

The endless belts mentioned above by which a resin threads are entangledis liable to be damaged due to the heat, etc., so that there is a fearof encountering a problem concerning the durability of the endlessbelts.

Therefore, the invention provides a method of and an apparatus formanufacturing a three-dimensional netted structure, capable of renderingit unnecessary to carry out a finishing operation in a later stage,improving the degree of straightness of the side surfaces of the nettedstructure, meeting a demand for finishing the netted structure tomodified shapes, and improving the durability of the netted structure.

SUMMARY OF THE INVENTION

In view of these various problems, in certain embodiments, the inventionis directed to a three-dimensional netted structure manufactured bypreparing a thermoplastic resin as a raw material or a main rawmaterial; forming the resin into a plurality of helically and randomlyentangled, partly and thermally bonded filaments by extrusion molding;and cooling the resultant filaments with water so as to obtain a nettedstructure having sparse and dense portions arranged alternately in thematerial extruding direction. This enables the netted structure to beapplied to a cushioning material and the like which is made possible tobe hung at a sparse portion thereof on a hook.

In particular, provided is a three-dimensional netted structure having anetted structure being manufactured by preparing a thermoplastic resinas a raw material or a main raw material, wherein the resin is formedinto a plurality of helically and randomly entangled, partly andthermally bonded filaments by extrusion molding; and the resultantfilaments are cooled with a liquid so as to obtain a netted structurehaving hollow portions arranged continuously in the material extrudingdirection, the structure is a three-dimensional plate type nettedstructure that the apparent density is 0.02 to 0.9 g/cm³, havingregenerated members inserted in the hollow portions.

In particular, provides is a three-dimensional netted structurecomprising: a netted structure being manufactured by preparing athermoplastic resin as a raw material or a main raw material; and aplurality of hollow portions which are spaced apart and formed in thenetted structure, wherein the hollow portions extend within the nettedstructure from one end to another end of the netted structure, whereinthe resin is formed into a plurality of helically and randomlyentangled, partly and thermally bonded filaments by extrusion molding,wherein the filaments are cooled with a liquid so as to obtain the anetted structure having the hollow portions arranged continuously in amaterial extruding direction, and wherein the netted structure is athree-dimensional plate type netted structure having an apparent densityof 0.02 to 0.9 g/cm³.

In other embodiments, the invention is directed to a three-dimensionalnetted structure manufactured by preparing a thermoplastic resin as araw material or a main raw material; forming the resin into a pluralityof helically and randomly entangled, partly and thermally bondedfilaments by extrusion molding; and cooling the resultant filaments witha liquid so as to obtain a netted structure having hollow portionsarranged in the material extruding direction. This enables the hollowportions to be utilized effectively by inserting other members thereinor by using the hollow portions in a different manner, and the nettedstructure to be thereby applied to various uses.

In particular provided is a three-dimensional netted structure having anetted structure being manufactured by preparing a thermoplastic resinas a raw material or a main raw material, wherein the resin is formedinto a plurality of helically and randomly entangled, partly andthermally bonded filaments by extrusion molding; and the resultantfilaments are cooled with a liquid so as to obtain a sheet having apercentage of void of zero continuously in the material extrudingdirection, forming the sheet into wavy shape in the material extrudingdirection, the structure is a three-dimensional plate type nettedstructure that the apparent density is 0.02 to 0.9 g/cm³.

In particular provided is a three-dimensional netted structurecomprising: a netted structure being manufactured by preparing athermoplastic resin as a raw material or a main raw material; and asheet which is included in an internal portion of the netted structure,wherein the sheet is formed in a wavy pattern and extends from one endto another end of the netted structure, wherein the resin is formed intoa plurality of helically and randomly entangled, partly and thermallybonded filaments by extrusion molding, wherein the resultant filamentsare cooled with a liquid so as to obtain a netted structure whichincludes the sheet having a percentage of void of zero continuously in amaterial extruding direction, thereby forming the sheet into the wavypattern in the netted structure in the material extruding direction, andwherein the netted structure is a three-dimensional plate type nettedstructure having an apparent density of 0.02 to 0.9 g/cm³.

In other embodiments, the invention is described to a three-dimensionalnetted structure manufactured by preparing a thermoplastic resin as araw material or a main raw material; forming the resin into a pluralityof helically and randomly entangled, partly and thermally bondedfilaments by extrusion molding; and cooling the resultant filaments witha liquid so as to obtain a sheet having a percentage of void ofsubstantially zero in the material extruding direction. This enables thesoundproofing and shock absorbing performance of the sheet to beimproved.

In other embodiments, the invention is directed to a three-dimensionalnetted structure manufactured by preparing a thermoplastic resin as araw material or a main raw material; forming the resin into a pluralityof helically and randomly entangled, partly and thermally bondedfilaments by extrusion molding; and cooling the resultant filaments witha liquid so as to obtain a netted structure having not smaller than twoseparable regions. This enables the difficulty, which was encountered ina related art netted structure of this kind, in recycling a complexresin and the like to be overcome by providing the netted structure withnot smaller than two separable regions.

In other embodiments, the invention is directed to a three-dimensionalnetted structure manufactured by preparing a thermoplastic resin as araw material or a main raw material; forming the resin into a pluralityof helically and randomly entangled, partly and thermally bondedfilaments by extrusion molding; and cooling the resultant filaments witha liquid so as to obtain an insulating material or a sound absorbingmaterial. This enables the netted structure to be used as a buildingmaterial, an interior finishing material for automobiles, and materialsfor similar purposes.

In other embodiments, the invention is directed to a three-dimensionalnetted structure manufactured by preparing a thermoplastic resin as araw material or a main raw material; forming the resin into a pluralityof helically and randomly entangled, partly and thermally bondedfilaments by extrusion molding; cooling the resultant filaments with aliquid; and applying a fire-resistant material to the cooled filamentsor enclosing the cooled filaments with the same material or adding thesame material to the cooled filaments. This enables the reliability ofan interior heat insulating material, an exterior heat insulatingmaterial, an interior finishing material for a side wall and an interiorfinishing material for automobiles to be improved.

In other embodiments, the invention is directed to a three-dimensionalnetted structure manufactured by preparing a thermoplastic resin as araw material or a main raw material; forming the resin into a pluralityof helically and randomly entangled, party and thermally bondedfilaments by extrusion molding; and cooling the resultant filaments witha liquid so as to obtain a seedbed for planting trees on a roof. Thisenables the recycling of the seedbed to be done, and the planting oftrees on a roof to be promoted.

In other embodiments, the invention is directed to a three-dimensionalnetted structure manufactured by preparing a thermoplastic resin as araw material or a main raw material; forming the resin into a pluralityof helically and randomly entangled, partly and thermally bondedfilaments by extrusion molding; and cooling the resultant filaments witha liquid so as to obtain a gardening cushioning material. This enablesthe netted structure to be used instead of a wooden trellis, and thedurability thereof to be improved.

In other embodiments, the invention is directed to a three-dimensionalnetted structure manufactured by preparing a thermoplastic resin as araw material or a main raw material; forming the resin into a pluralityof helically and randomly entangled, partly and thermally bondedfilaments by extrusion molding; and cooling the resultant filaments witha liquid so as to obtain a netted structure having polyhedral ormiscellaneously shaped side surfaces.

In other embodiments, the invention is directed to a three-dimensionalnetted structure manufactured by preparing a regenerated thermoplasticresin, especially, polyethylene terephthalate as a raw material or amain raw material; forming the resin into a plurality of helically andrandomly entangled, partly and thermally bonded filaments by extrusionmolding; and cooling the resultant filaments with a liquid so as toobtain a recycled netted structure. This enables the recovery ofpolyethylene terephthalate bottles, etc. to be promoted.

In other embodiments, the invention is directed to a three-dimensionalnetted structure manufactured by preparing a brittleness-causing rawmaterial-containing thermoplastic resin as a raw material or a main rawmaterial; forming the resin into a plurality of helically and randomlyentangled, partly and thermally bonded filaments by extrusion molding,and cooling the resultant filaments with a liquid so as to obtain anetted structure capable of being brittle fractured by applying anexternal force thereto. This enables a shock occurring due to thecollision of a vehicle to break the texture of the three-dimensionalnetted structure, so that damage to a vehicle due to the collisionthereof can be prevented.

In particular, provided is a three-dimensional netted structure having anetted structure being manufactured by preparing thermoplastic resin asa raw material or a main raw material containing a theness-causing rawmaterial; wherein the resin is formed into a plurality of helically andrandomly entangled, partly and thermally bonded filaments by extrusionmolding; and the resultant filaments are cooled with a liquid so as toobtain a netted structure capable of the fractured by applying anexternal force thereto after cooling and hardening.

In particular, provided is a three-dimensional netted structurecomprising: a netted structure being manufactured by preparingthermoplastic resin as a raw material or a main raw material containinga brittleness-causing raw material, wherein the resin is formed into aplurality of helically and randomly entangled, partly and thermallybonded filaments by extrusion molding, wherein the filaments areextruded along a plane in a single direction to form the nettedstructure, wherein the filaments upon being extruded are cooled with aliquid so as to obtain a netted structure having hardened filaments, andwherein the netted structure is brittle and can be fractured by applyingan external force of a predetermined amount thereto.

In other embodiments, the invention is directed to a three-dimensionalnetted structure comprising: a netted structure being manufactured bypreparing a thermoplastic resin as a raw material or a main rawmaterial, wherein the netted structure includes an inner region having apredetermined apparent density and an outer peripheral region adjacentthe inner region having an apparent density higher than thepredetermined apparent density, wherein the resin is formed into aplurality of helically and randomly entangled, partly and thermallybonded filaments by extrusion molding, wherein the filaments are cooledwith a liquid so as to obtain the netted structure having the innerregion and the outer peripheral region arranged continuously in amaterial extruding direction, and wherein the netted structure is athree-dimensional plate type netted structure having the predeterminedapparent density and the apparent density greater than the predeterminedapparent density of 0.02 to 0.9 g/cm³.

In other embodiments, the invention is directed to a three-dimensionalnetted structure formed out of a thermoplastic resin as a raw materialor a main raw material by extrusion molding, in which a plurality offilaments are helically and randomly entangled and thermally bondedtogether and the resultant filaments are cooled with a liquid so as toobtain the netted structure having upper and lower surfaces, two sidesurfaces and left and right end surfaces; characterized in that thestructure is four-surface molded wherein the upper and lower surfacesand the two side surfaces are molded.

In a class of this embodiment, the structure additionally comprises asubstantially non-void-carrying sheet, which forms a wavy shape in thematerial extruding direction.

In a class of this embodiment, the apparent density of the nettedstructure is 0.02 to 0.9 g/cm³.

In a class of this embodiment, the netted structure has sparse and denseportions arranged alternately in the material extruding direction.

In a class of this embodiment, the netted structure has a single or aplurality of beam-like high-density regions arranged in the direction ofthe thickness of the netted structure.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure which is obtained byextruding molten filaments of a thermoplastic resin, a raw material or amain raw material downward from a die having a plurality of holes;having the filaments drop naturally between partly-submergeddrawing-down units; when a three-dimensional netted structure ismanufactured by drawing the filaments between the drawing-down units ata speed lower than a filament dropping speed, a distance between thedrawing-down units being set smaller than a width of an assembly of theextruded filaments, the drawing-down units being arranged so that atleast three or four surfaces of the assembly of the filaments contactthe drawing-down units before or after the drawing-down units aresubmerged. This renders it unnecessary to carry out a finishingoperation in a later stage, and enables the degree of straightness ofthe side surfaces of the netted structure to be heightened.

In particular provided is an apparatus for manufacturing athree-dimensional netted structure having a netted structure beingobtained by extruding molten filaments of a thermoplastic resin as a rawmaterial or a main raw material, comprising: a die having a plurality ofholes, the filaments being downward from the die; and drawing-down unitspartly-submerged in water, having the filaments drop naturally inbetween; wherein the drawing-down units draw the filaments in between ata speed lower than a filament dropping speed, a distance between thedrawing-down units being set smaller than a width of an assembly of theextruded filaments, and the drawing-down units are arranged so that foursurfaces of the assembly of the filaments contact the drawing-down unitsbefore or after the drawing-down units being submerged, driving systemsof the opposite drawing-down units are formed by fixing.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure which is obtained byextruding molten filaments of a thermoplastic resin, a raw material or amain raw material downward from a die having a plurality of holes;having the filaments drop naturally between partly-submerged rollers;and drawing the filaments between the rollers at a speed lower than afilament dropping speed, a distance between the rollers being setsmaller than a width of an assembly of the extruded filaments, at leastone surface of the assembly of the filaments contacting the rollersbefore or after the rollers are submerged. This enables the simplicityof the apparatus and the easiness of designing the apparatus to beattained.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure which is obtained byextruding molten filaments of a thermoplastic resin, a raw material or amain raw material downward from a die having a plurality of holes;having the filaments drop naturally between partly-submerged, slidablesurface-carrying plate members a distance between which is set so as todecrease gradually in the downward direction; and drawing the resultantfilaments between the plate members at a speed lower than a filamentdropping speed, a distance between lower portions of the plate membersbeing set smaller than a width of an assembly of the extruded filaments,at least one surface of the assembly of the filaments contacting theplate members before or after the plate members are submerged. Thisenables the miniaturization of the apparatus to be attained by reducingor omitting movable parts.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure which is obtained byextruding molten filaments of a thermoplastic resin, a raw material or amain raw material downward from a die having a plurality of holes;having the filaments drop naturally between partly submergeddrawing-down units; and drawing the filaments between the drawing-downunits at a speed lower than a filament dropping speed, a distancebetween the drawing-down units being set smaller than a width of anassembly of the extruded filaments, at least one surface of the assemblyof the filaments contacting the drawing-down units before or after thedrawing-down units are submerged, a cross section of outercircumferential members of the drawing-down units being set to modifiedshapes. This enables an operation in a later stage to be omitted.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure which is obtained byextruding molten filaments of a thermoplastic resin, a raw material or amain raw material downward from a die having a plurality of holes;having the filaments drop naturally between partly-submergeddrawing-down units; and drawing the filaments between the drawing-downunits at a speed lower than a filament dropping speed, a distancebetween the drawing-down units being set smaller than a width of anassembly of the extruded filaments, at least one surface of the assemblyof the filaments contacting the drawing-down units before or after thedrawing-down units are submerged, the die being provided with a complexdie which has not smaller than two chambers and a plural-hole-carryingmouthpiece, the molten filaments of a thermoplastic resin, a rawmaterial or a main raw material being extruded downward from the holesof the mouthpiece via different passages isolated from one another bypartitions. This enables a separable three-dimensional netted structureto be manufactured.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure which is obtained byextruding molten filaments of a thermoplastic resin, a raw material or amain raw material downward from a die having a plurality of holes;having the filaments drop naturally between partly-submergeddrawing-down units; and drawing the resultant filaments between thedrawing-down units at a speed lower than a filament dropping speed, adistance between the drawing-down units being set smaller than a widthof an assembly of the extruded filaments, at least one surface of theassembly of the filaments contacting the drawing-down units before orafter the drawing-down units are submerged, the drawing-down units beingprovided with circumferentially moving members, which are provided atcircumferences thereof with circumferentially extending metal nets orplate members. This enables the durability of the drawing-down units tobe improved.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure which is obtained byextruding molten filaments of a thermoplastic resin, a raw material or amain raw material downward from a die having a plurality of holes;having the filaments drop naturally between partly-submergeddrawing-down units; and drawing the filaments between the drawing-downunits at a speed lower than a filament dropping speed, a distancebetween the drawing-down units being set smaller than a width of anassembly of the extruded filaments, at least one surface of the assemblyof the filaments contacting the drawing-down units before or after thedrawing-down units are submerged, regions of a high density of holes andregions of a low density of holes being formed on a mouthpiece of thedie. This enables the range of designing of the apparatus to be widened.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure having a nettedstructure being obtained by extruding molten filaments of athermoplastic resin as a raw material or a main raw material,comprising: a die having a plurality of holes, the filaments beingdownward from the die; and drawing-down units partly submerged in water,having the filaments drop naturally in between; and wherein thedrawing-down units draw the filaments in between at a speed lower than afilament dropping speed, a distance between the drawing-down units isset smaller than a width of an assembly of the extruded filaments, atleast one surface of the assembly of the filaments contact thedrawing-down units before or after the drawing-down units beingsubmerged, forming a slit in a suitable portion of a mouthpiece.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure having a nettedstructure being obtained by extruding molten filaments of thermoplasticresin as a raw material or a main raw material containing a thenesscausing raw material, comprising: a die having a plurality of holes, thefilaments being downward from the die; and drawing-down unitspartly-submerged in water, having the filaments drop naturally inbetween; wherein the drawing-down units draw the filaments in between ata speed lower than a filament dropping speed, a distance between thedrawing-down units being set smaller than a width of an assembly of theextruded filaments, and the drawing-down units are arranged so that atleast one surface of the assembly of the filaments contact thedrawing-down units before or after the drawing-down units beingsubmerged, the netted structure capable of the fractured by applying anexternal force thereto.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure, as described herein,having a netted structure being obtained by extruding molten filamentsof a thermoplastic resin as a raw material or a main raw material,comprising: a die having a plurality of holes, the filaments beingdownward from the die; and drawing-down units partly-submerged in water,having the filaments drop naturally in between, wherein the drawing-downunits draw the filaments in between at a speed lower than a filamentdropping speed, a distance between the drawing-down units being setsmaller than a width of an assembly of the extruded filaments, whereinthe drawing-down units are arranged so that four surfaces of theassembly of the filaments contact the drawing-down units before or afterthe drawing-down units being submerged, wherein a curved plate extendsbetween the die and the draw-down unit thereby introducing the filamentsto the draw-down unit, and wherein the curved plate is given at theirouter surfaces having a slidability, the curved plate is arranged sothat a distance inbetween decreases from upper portions thereof towardlower portions thereof.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure having a nettedstructure being obtained by extruding molten filaments of athermoplastic resin as a raw material or a main raw material, theapparatus comprising: a die, a mouthpiece of the die having a pluralityof holes, the filaments being extruded downward from the die via themouthpiece; and drawing-down units partly-submerged in liquid, havingthe filaments drop in between; wherein the drawing-down units draw thefilaments in between at a speed lower than the filament dropping speed,and the distance between the drawing-down units is set smaller than thewidth of the assembly of the extruded filaments, and wherein thedrawing-down units are arranged so that four surfaces of the assembly ofthe filaments contact the drawing-down units before or after thedrawing-down units are submerged.

In a class of this embodiment, the mouthpiece has a slit in addition tothe plurality of holes, the slit extending in the lengthwise directionof the mouthpiece, whereby the three dimensional netted structureadditionally comprises a substantially non-void-carrying sheet, thenon-void-carrying sheet forming a wavy shape in the material extrudingdirection.

In another class of this embodiment, the mouthpiece has a region notprovided with holes so as to make a hollow portion in thethree-dimensional netted structure arranged in the material extrudingdirection.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure, the netted structurecomprising: a netted structure being manufactured by preparing athermoplastic resin as a raw material or a main raw material; and asheet which is included in an internal portion of the netted structure,wherein the sheet is formed in a wavy pattern and extends from one endto another end of the netted structure, wherein the resin is formed intoa plurality of helically and randomly entangled, partly and thermallybonded filaments by extrusion molding, wherein the filaments are cooledwith a liquid so as to obtain the netted structure which includes thesheet having a percentage of void of zero continuously in a materialextruding direction, thereby forming the sheet into the wavy pattern inthe netted structure in the material extruding direction, and whereinthe netted structure is a three-dimensional plate type netted structurehaving an apparent density of 0.02 to 0.9 g/cm3; the apparatuscomprising: a die, a mouthpiece of the die having a plurality of holes,the filaments being extruded downward from the die via the mouthpiece;and drawing-down units partly-submerged in liquid, having the filamentsdrop in between; wherein the drawing-down units draw the filaments inbetween at a speed lower than the filament dropping speed, and thedistance between the drawing-down units is set smaller than the width ofthe assembly of the extruded filaments, and wherein the drawing-downunits are arranged so that four surfaces of the assembly of thefilaments contact the drawing-down units before or after thedrawing-down units are submerged.

In a class of this embodiment, the mouthpiece has a slit in addition tothe plurality of holes, the slit extending in the lengthwise directionof the mouthpiece, whereby the three dimensional netted structureadditionally comprises a substantially non-void-carrying sheet, thenon-void-carrying sheet forming a wavy shape in the material extrudingdirection.

In another class of this embodiment, the mouthpiece has a region notprovided with holes so as to make a hollow portion in thethree-dimensional netted structure arranged in the material extrudingdirection.

In other embodiments, the invention is directed to an apparatus formanufacturing a three-dimensional netted structure as described herein,comprising: a die, a mouthpiece of the die having a plurality of holes,the filaments being extruded downward from the die via the mouthpiece;and, drawing-down units partly-submerged in liquid, having the filamentsdrop in between; wherein the drawing-down units draw the filaments inbetween at a speed lower than the filament dropping speed, and thedistance between the drawing-down units is set smaller than the width ofthe assembly of the extruded filaments, characterized in that thedrawing-down units are arranged so that four surfaces of the assembly ofthe filaments contact the drawing-down units before or after thedrawing-down units are submerged.

In a class of this embodiment, the mouthpiece has a slit in addition tothe plurality of holes, the slit extending in the lengthwise directionof the mouthpiece such that the three dimensional netted structureadditionally comprises a substantially non-void-carrying sheet whichforms a wavy shape in the material extruding direction.

In a class of this embodiment, the mouthpiece has a region not providedwith holes so as to make a hollow portion in the three-dimensionalnetted structure arranged in the material extruding direction.

In other embodiments, the invention is directed to a method ofmanufacturing a three-dimensional netted structure as described herein,by extruding molten filaments of a thermoplastic resin downward from adie via a mouthpiece of the die having a plurality

of holes, such that the filaments drop in between drawing-down unitspartly-submerged in liquid and the distance between the drawing-downunits is set smaller than the width of the assembly of the extrudedfilaments; drawing down the assembly of extruded filaments at a speedlower than the filament dropping speed and, cooling the resultantfilaments with a liquid, characterized in that the drawing down is bydrawing-down units arranged so that four surfaces of the assembly of thefilaments contact the drawing-down units before or after thedrawing-down units are submerged.

In a class of this embodiment, the mouthpiece has a slit in addition tothe plurality of holes, the slit extending in the lengthwise directionof the mouthpiece such that the three dimensional netted structureadditionally comprises a substantially non-void-carrying sheet whichforms a wavy shape in the material extruding direction.

In a class of this embodiment, the mouthpiece has a region not providedwith holes so as to make a hollow portion in the three-dimensionalnetted structure arranged in the material extruding direction.

In other embodiments, the invention is directed to a method ofmanufacturing a three-dimensional netted structure, the method beingapplied to form netted structures described herein.

In other embodiments, the invention is directed to a method ofmanufacturing a three-dimensional netted structure, comprising applyingthe apparatus described herein to form a netted structure.

In other embodiments, the invention is directed to a method ofmanufacturing a three-dimensional netted structure, comprising applyingthe apparatus described herein to form a netted structure describedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a three-dimensional netted structure ofan exemplary embodiment of the invention;

FIG. 2A is a longitudinal sectional view of the three-dimensional nettedstructure of an exemplary embodiment of the invention;

FIG. 2B is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 2C is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 2D is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 2E is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 2F is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 2G is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 3A is a longitudinal sectional view of the three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 3B is a side view of the three-dimensional netted structure ofanother exemplary embodiment of the invention;

FIGS. 4A to 4G are sectional views of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 5 is a perspective view of an apparatus for manufacturing thethree-dimensional netted structure of an exemplary embodiment of theinvention;

FIG. 6 is an explanatory drawing showing the condition of an operationof the apparatus for manufacturing the three-dimensional nettedstructure of an exemplary embodiment of the invention;

FIGS. 7A and 7B are a side view and a front view, respectively, ofendless conveyors in the same apparatus for manufacturing thethree-dimensional netted structure;

FIGS. 8A to 8F are side views of modified modes of endless conveyors inthe same apparatus for manufacturing the three-dimensional nettedstructure;

FIG. 9A is a plan view of endless conveyors for an apparatus formanufacturing a four-surface-molded three-dimensional netted structure;

FIG. 9B is a side view of the same apparatus for manufacturing thethree-dimensional netted structure;

FIG. 9C is a side view of another exemplary embodiment of the apparatusfor manufacturing a four-surface-molded three-dimensional nettedstructure;

FIG. 9D is a plan view showing the condition of a four-surface moldingoperation carried out by the same apparatus for manufacturing thethree-dimensional netted structure;

FIG. 9E is a plan view showing the condition of a three-surface moldingoperation carried out by the same apparatus for manufacturing thethree-dimensional netted structure;

FIG. 10A is a plan view of endless conveyors in an apparatus of anindependent driving system for manufacturing a four-surface-moldedthree-dimensional netted structure;

FIG. 10B shows endless conveyors provided with sliding plates at endsurfaces thereof in an apparatus for manufacturing a three-dimensionalnetted structure;

FIGS. 11A to 11H are plan views and a front view showing variousexemplary embodiments of mouthpieces of a die;

FIGS. 12A and 12B are front views of modified modes of endlessconveyors, which are used for carrying out a four-surface moldingoperation, in an apparatus for manufacturing a three-dimensional nettedstructure;

FIG. 13A is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 13B is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 13C is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 13D is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 14A is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 14B is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 14C is a longitudinal sectional view of a three-dimensional nettedstructure of another exemplary embodiment of the invention;

FIG. 15 is a perspective view of the apparatus for manufacturing athree-dimensional netted structure of another exemplary embodiment ofthe invention;

FIG. 16A is a horizontal sectional view showing the portion of theapparatus for manufacturing a three-dimensional netted structureaccording to the invention which is in the vicinity of an upper part ofa mouthpiece of a complex die;

FIG. 16B is a front view of a lower portion of the complex die accordingto an exemplary embodiment of the invention;

FIGS. 17A and 17B are drawings illustrating other exemplary embodimentsof the apparatus for manufacturing a three-dimensional netted structure;

FIGS. 18A, 18B and 18D are plan views showing other exemplaryembodiments of mouthpieces of dies;

FIG. 18C is a front view of the mouthpiece shown in FIG. 18D;

FIGS. 19A to 19D are plan views showing exemplary embodiments of themouthpieces of the dies;

FIG. 20 is an explanatory drawing showing the condition of an operationof another exemplary embodiment of the apparatus for manufacturing athree-dimensional netted structure;

FIGS. 21A and 21B are side views and front views, respectively, of rollsin the same apparatus for manufacturing a three-dimensional nettedstructure;

FIGS. 22A to 22G are side views of other embodiments of rolls in thesame apparatus for manufacturing a three-dimensional netted structure;

FIG. 23A is a front view of the three-dimensional netted structure(applied to a gardening cushioning material and the like) of anotherexemplary embodiment of the invention;

FIG. 23B is a plan view of the same three-dimensional netted structure;

FIG. 23C is a side view of the same three-dimensional netted structure;

FIG. 23D shows another exemplary embodiment of the three-dimensionalnetted structure;

FIG. 24A is a plan view of a mouthpiece of a die in another exemplaryembodiment of the apparatus for manufacturing a three-dimensional nettedstructure;

FIG. 24B is a front view thereof;

FIG. 24C is a plan view of a mouthpiece of another die;

FIG. 24D is a front view thereof;

FIG. 25 is an explanatory drawing showing the condition of use ofanother exemplary embodiment of the three-dimensional netted structure;

FIG. 26 is an explanatory drawing showing the condition of another useof another exemplary embodiment of the three-dimensional nettedstructure; and

FIG. 27 is a construction diagram of a part of another exemplaryembodiment of the apparatus for manufacturing a three-dimensional nettedstructure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIGS. 1 and 2A, a three-dimensional netted structure 1 is athree-dimensional netted structure the characteristics of which residein that the structure is a three-dimensional plate type netted structureformed out of a regenerated thermoplastic resin as a raw material or amain raw material, in which a plurality of filaments are helically andrandomly entangled and partly and thermally bonded together and have twoside surfaces, left and right end surfaces and upper and lower endsurfaces. It is preferable that the density of surface-side portions ofthree surfaces out of the side surfaces of this three-dimensional nettedstructure be relatively higher than that of the portion exclusive of thementioned surface-side portions. Namely, referring to FIG. 2A, thethree-dimensional netted structure 1 is in this embodimentthree-surface-molded. In this structure, regions thereof which extendinward from the opposite surfaces thereof by a predetermined distanceare molded to a high density, and the density of a region which extendsin a central inner portion of the netted structure is set lower than thementioned density. Thus, the remaining one surface of the structure hasa non-straight extending surface. Therefore, this netted structure hasan advantage in being not subjected to a process in a later stage. Inshort, a pair of surfaces of a large width and one side surface areforcibly molded by endless conveyors and the like which will bedescribed later, and the edges of these surfaces are formed moreesthetically pleasing than that of the other surface.

In this embodiment, flaked or chipped PET bottles are used as a rawmaterial or a main raw material of the regenerated thermoplastic resin.The raw material is obtained by pulverizing unmodified PET bottles,melting the pulverized products, and forming the molten product intoflakes. This material is suited to the recycling promoting age. When thematerial is not a recycled product but a genuine product, themanufacturing cost per 1 square meter of the netted structure doublesdue to the dry crystallization of or the removal of waste from thematerial. The material used in this embodiment allows for a reduction ofthe product scrapping cost. However, this embodiment can also be appliedto a thermoplastic resin and the like other than regenerated materialsof this kind For example, polyolefines, such as polyethylene,polypropylene, etc., polyesters, such as polyethylene terephthalate,etc. polyamides, such as nylon 66, etc, polyvinyl chloride, polystyrene,a copolymer and an elastomer obtained by copolymerizing these resins asbase materials, a material obtained by blending these resins, and someother similar materials.

The three-dimensional netted structure, is used mainly as a cushioningmaterial, a shock absorbing material, a moisture absorbing material, asound absorbing material (to be provided under a floor material, in aninner portion of a structure and inside a wall), a heat insulatingmaterial (inner and outer heat insulating purposes), a wall surfacematerial, a roof gardening material, a concrete and mortar crackingpreventing material, interior finishing material for automobiles, andhas some other uses. This netted structure can also be applied to aninner portion of a double wall.

When a fire resistant material is mixed with the three-dimensionalnetted structure by holding the three-dimensional netted structurebetween nonwoven cloths or by attaching such cloths thereto, andapplying fire resistant paint to the netted structure, so as to givefire resistance to the three-dimensional netted structure, the resultantnetted structure becomes more preferable as a heat insulating buildingmaterial, a sound absorbing building material and the like.

The netted structure in this embodiment is molded so as to have asubstantially uniform density at an inner portion thereof. The apparentdensity of this embodiment is preferably 0.02 to 0.9 g/cm³(corresponding to a percentage of void of 36 to 98.4%), and especiallypreferably 0.05 to 0.15 g/cm³. The three-dimensional netted structure 1preferably has, for example, a width of 0.1 m to 2 m and a thickness of5 mm to 200 mm, and extends endlessly in the lengthwise direction. Thenetted structure is cut to a suitable length (for example, 90 mm) butthe sizes of the netted structure are not limited to the examplesmentioned above.

Referring to FIG. 2B, a three-dimensional netted structure 2 of anotherexemplary embodiment is four-surface-molded, and all the surfaces of thenetted structure extend straight. This netted structure is formed sothat the density of the regions thereof which correspond to those of thethree-dimensional netted structure 1, and which extend inward from theleft and right surfaces of the netted structure toward an inner portionthereof by a predetermined distance, becomes high, and so that thedensity of the region of the netted structure which is at a centralinner portion thereof be set lower than the mentioned density. Namely,the regions of the netted structure which extends from all the surfacesthereof except the upper and bottom surfaces thereof to an inner portionof the netted structure by a predetermined distance are molded to adensity higher than the above-mentioned density.

In another embodiment, a three-dimensional netted structure 3 has asurface of modified shapes or a polyhedral surface. With reference to,this type of netted structures include, for example, a netted structure3A provided with a convex surface (FIG. 4A) a netted structure 3Bprovided with a concave surface (FIG. 4B), a netted structure 3Cprovided with a plurality of continuously formed projecting and recessedportions (FIG. 4C), a netted structure 3D provided with a plurality ofsaw-tooth-like portions (FIG. 4D), a netted structure 3E provided with aplurality of wavy portions (FIG. 4E), a netted structure 3F providedwith rounded corner portions (FIG. 4F), a netted structure 3G providedwith cut corner portions of a predetermined angle, e.g., 45° (FIG. 4G),or a suitable combination thereof, etc.

In the field of construction, various types of netted structures aredemanded as products, and these embodiment can meet a demand for suchnetted structures. It is considered that forming netted structures ofcomplicated shapes causes various uses thereof to be newly found.Especially, forcibly molding three or four surfaces of thethree-dimensional netted structure as in the above-described first andsecond modes of embodiment enables the various demands for the productsto be met. Furthermore, in order to obtain netted structures ofmiscellaneous surface shapes, netted structures are generally cut ormolded so as to provide surfaces of modified shapes thereon on a laterstage. According to this mode of embodiment, products can be providedinstantly without finishing the netted structure as to the shape andsizes, which the products demand, on a later stage, so that a laterstage can be rendered unnecessary.

The three-dimensional netted structure 4 (shown in FIG. 2C) is providedwith a single or a plurality (two in this embodiment) of hollow portions4A, 4B, and aims at further reducing the manufacturing cost.

The three-dimensional netted structure 5 (shown in FIG. 2D) hasregenerated members 5C, 5D of the same or different materials, such asplate type regenerated veneer members, plate type members of regeneratedshredder dust and the like inserted in hollow portions 5A, 5B identicalwith the hollow portions 4A, 4B of the three-dimensional nettedstructure 4. This embodiment aims at improving the sound absorbability,heat insulating characteristics, cushioning characteristics and the likeof the netted structure by using regenerated plate members.

In the three-dimensional netted structure 6 (shown in FIG. 2E), thesound absorbing characteristics, heat insulating characteristics,cushioning characteristics and impact resistance are improved byincreasing the density of parts of the inner portion of thethree-dimensional netted structure 1 in the direction of the thicknessthereof, and thereby partly forming a single or a plurality (e.g., threein this embodiment) of beam-like high-density regions 6A, 6B and 6C atpredetermined intervals.

In the three-dimensional netted structure 7 (shown in FIG. 2F), thesound absorbing characteristics, heat insulating characteristics,cushioning characteristics and impact resistance thereof are improved byincreasing the density of parts of the inner portion thereof in thewidthwise direction thereof, and thereby partly forming a plurality (onein this embodiment) of or a single high-density region 7A.

In the three-dimensional netted structure 8 (shown in FIG. 2G), thesound absorbing characteristics, heat insulating characteristics,cushioning characteristics and impact resistance are improved by forminga wavy high-density region 8A in an inner portion of thethree-dimensional netted structure 7.

In the three-dimensional netted structure 9 (shown in FIG. 3A), thesound absorbing characteristics, heat insulating characteristics,cushioning characteristics and impact resistance are improved by forminga sheet 9A (a non-void-carrying region) in a predetermined widthwiseextending inner portion of the three-dimensional netted structures 1 or2. Around the sheet 9A, filaments (resin threads) are entangled with oneanother. The sheet 9A may be provided fully in the lateral direction asshown in the drawing, and also partly, for example, in the centralportion and the like.

The sheet 9A in the three-dimensional netted structure 9 (shown in FIG.3B) is wave form in general and the sound absorbing characteristics,heat insulating characteristics, cushioning characteristics and impactresistance of the netted structure are improved. The reason for why thesheet 9A can be molded in wave form resides in that a draw-down speed ofrolls is lower than a resin thread dropping speed, as will be describedin more detail later. The intervals, height and width of the waves ofthe sheet 9A differ depending upon the manufacturing conditions, and arenot limited to those shown in the drawing. When the intervals of thewaves of the sheet 9A are small, the waves are bonded to one another insome cases. The three-dimensional netted structure 9 can be manufacturedby using a slit (linear through hole) 75 a shown in FIG. 11E.

Although illustrations are omitted, the invention can also be applied tothree-dimensional netted structures of modified cross-section shapes,such as a triangular cross-section shape, a Y-type cross-section shapeand the like.

Apparatus for Manufacturing a Three-Dimensional Netted Structure

An apparatus 10 for manufacturing a three-dimensional netted structurewill now be described.

As shown in FIG. 5, the apparatus 10 for manufacturing athree-dimensional netted structure, comprises: an extrusion moldingmachine 11, a pair of endless conveyors 14, 15 (shown in FIG. 7)provided with endless members 12, 13, a motor 16 adapted to drive theendless members 12, 13, a transmission 17 formed of a chain and a gearand adapted to change a moving speed of the endless members 12, 13, awater tank 18 adapted to partly submerge the two endless conveyors 14,15 therein, a control unit 19, and other meters, etc.

The endless members 12, 13 are formed by fixing with screws (not shown)a plurality of metal plate members 21 (made of stainless steel and thelike in this embodiment) to a plurality of endless chains 12 a, 13 a(two for each conveyor) (see FIGS. 7A and 7B) with a predetermined widthof clearance 22 (refer to FIG. 8A) left therebetween. Instead of theseplate members, a belt 23 of a stainless steel mesh (metal net) whichdoes not have the clearance 22 may also be used as shown in FIG. 8B.This mesh belt is formed by combining spiral wires with rods (powerribs), and various types of mesh belts are formed by varying the shapes,diameters and pitch of these two elements. Such mesh belts movesmoothly, keep the smooth belt surfaces horizontal excellently, standuse in hot temperature condition excellently, and are repaired simply.

As shown by dotted lines in FIG. 7, stainless mesh belts 23 passedaround outer circumferences of the endless members 12, 13 can also beused in practice, and are preferably used when it is desirable toprevent the occurrence, which is ascribed to the presence of theclearance 22, of recessed and projecting portions on the mesh belt. Thecross section of the plate member 21 is rectangular, and variousmodified modes of plate members 21 are conceivable, which include aconvex plate member 24 (FIG. 8C), a concave plate member 25 (FIG. 8D), asaw-tooth plate member 26 (FIG. 8E), a continuously recessed andprojecting plate member 27 (FIG. 8F), etc.

As shown in FIG. 7, the endless conveyor 14 is provided with a drivingshaft 14 b having a sprocket 14 a around which the endless chain 12 aprovided vertically is passed, and a driven shaft 14 d having a sprocket14 c. The endless conveyor 15 is driven synchronously with the endlessconveyor 14, and provided with a driven shaft 15 b mounted with asprocket 15 a around which the endless chain 13 a is passed, and adriven shaft 15 d mounted with a sprocket 15 c.

As shown in FIG. 5, the extrusion molding machine 11 includes acontainer 31, a raw material feed port 32 provided on an upper portionof the container 31, a die 33, a mouthpiece 34 capable of being fixeddetachably to a lower end portion of the die 33. A range of thetemperature in an inner portion of the die of the extrusion moldingmachine 11 can be set to between 100 and 400° C., and an extrusion rateof the machine 20 to 200 kg/hr and the like. A range of the pressure inthe die is 0.2 to 25 MPa, which is equal to, for example, a dischargepressure of a 75 mm screw.

When the thickness of the three-dimensional netted structure exceeds 100mm, the equalization of the pressure in the die by a gear pump and thelike is needed in some cases. Therefore, it becomes necessary that thepressure in the die be increased by a gear pump and the like so as todischarge filaments uniformly from the whole region of the interior ofthe die. To meet the requirement, the surfaces of the endless conveyors14, 15 are formed so that these surfaces can be moved freely so as toset the shape of a three-dimensional netted sheet. This enables aproduct having desired density and strength to be manufactured inaccordance with the shape (density or diameter of the holes H) of themouthpiece 34 of the die 33 and a transfer speed of the endlessconveyors 14, 15, and various demands for the products to be met.

An apparatus 50 for manufacturing a three-dimensional netted structurewhich is made of such a four-surface-molding machine as shown in FIGS.9A and 9B will now be described. This apparatus 50 for manufacturing athree-dimensional netted structure is provided with endless conveyors54, 55 having rotary shafts 54 a, 55 a which correspond to the endlessconveyors 14, 15 used in a two-surface-molding operation, shown in FIG.7, and a pair of rolls 56, 57 disposed at lengthwise end portions of theendless conveyors 54, 55 and having rotary shafts 56 a, 57 a extendingat right angles to the shafts of the endless conveyors. The rotary shaft54 a is mounted with bevel gears 54 b, 54 c, while the rotary shafts 56a, 57 a are also mounted with bevel gears 56 b, 57 b. The bevel gears 54b, 54 c and the bevel gears 56 b, 57 b are meshed with each other, andthe rotary shafts 54 a, 55 a are driven synchronously by a motor M via achain C. Therefore, the rotary shafts 56 a, 57 a are also drivensynchronously. The other end portions of the rotary shafts 56 a, 57 aare supported on bearings 58 a, 58 b.

As shown in FIG. 9C, the apparatus may be an apparatus formed byarranging a pair of short endless conveyors 59 a, 59 b, the constructionof which is identical with the endless conveyors 54, 55, at right anglesto rotary shafts of rolls. In this case, the molding of a product can bedone more precisely, and the dimensional accuracy of a product isimproved.

As shown in FIG. 9D, the manufacturing of a three-dimensional nettedstructure can be done by using four-surface-molding techniques. Thethree-surface-molding of the product can also be done by using thementioned techniques as shown in FIG. 9E. Namely, when a certain type ofthree-dimensional netted structure is manufactured, two systems of diesare provided, and filaments are extruded in parallel. As a result, theproductive efficiency of the netted structure doubles.

As shown in FIG. 10A, an apparatus of a modified mode can be also usedwhich is formed by providing driving power sources (motors) instead ofthe previously-mentioned synchronous driving system so that endlessconveyors 64, 65 and rolls 66, 67 (endless conveyors also serve thepurpose) are driven independently of each other. Namely, in order tocarry out three-surface or four-surface-molding operation, endlessconveyors 64, 65 having rotary shafts 64 a, 65 a, and a pair of rolls66, 67 arranged at lengthwise end portions of these endless conveyors64, 65, and having rotary shafts 66 a, 67 a extending at right angles tothose of the endless conveyors are provided. The rotary shafts 66 a, 67a are also provided with respective motors M so that these rotary shaftsare driven independently of each other. The other end portions of therotary shafts 66 a, 67 a are supported on bearings 68 a, 68 b.

As shown in FIG. 10B, which shows another modified mode of theapparatus, in which a driving mechanism can be simplified by removingsuch two rolls 66, 67, two rotary shafts 66 a, 67 a, two bearings 68 a,68 b and two motors M as are provided in the preceding example, andproviding sliding curved plates 69 a, 69 b, the surfaces of which arecoated with polytetrafluoroethylene, in positions in which the rolls 66,67 were placed. These curved plates 69 a, 69 b are arcuate in sideelevation and positioned so that a distance between these curved platesdecreases gradually from upper portions thereof toward lower portionsthereof. The curved plates are formed to a rectangular shape in plan.

The holes of the mouthpiece 34 are downwardly made in series, from whichfilaments come out downward. The holes may be arranged at regularintervals or at non-regular intervals. The holes may employ staggered,orthogonal and various other types of configurations. When it is desiredthat the arrangement density of the holes be changed, a method ofpositively increasing the arrangement density thereof in end regionsonly is used in some cases. Changing the mode of the mouthpiecevariously enables various demands for the products to be met.Mouthpieces of a multiplicity of specifications can be used practicallywhich include, for example, a mouthpiece 71 (having holes H accountingfor 90% of the area of the mouthpiece 71) (refer to FIG. 11A) of 1.0m×180 mm in which about 3500 holes H of 0.5 mm in diameter are made, amouthpiece 72 (refer to FIG. 11B) in which the density of the holes H isset high only in a circumferential portion 72 a thereof, a mouthpiece 73(refer to FIG. 11C) in which the density of the holes H of frame-formingportion 73 b is increased so that the frame-forming portion constitutesseries-connected frames, a mouthpiece 74 (refer to FIG. 11D) in whichslits (linear through holes) 74 a to 74 c in addition to a multiplicityof holes H are formed so that the slits extend in parallel with shortersides of the mouthpiece, a mouthpiece 75 (refer to FIG. 11E) in which aslit (linear through hole) 75 a in addition to a multiplicity of holes His formed so that the slit extends in the lengthwise direction of themouthpiece, a mouthpiece 76 (refer to FIG. 11F) and the like in which aslit (linear through hole) 76 a in addition to a multiplicity of holes His formed so that the slit extends in a position near a lengthwise sideof the mouthpiece, and similar other mouthpieces, and a mouthpiece 77(refer to FIGS. 11G and 11H) and the like which have regions 77 c, 77 dnot provided with the holes H so as to make hollow portions therein, andwhich is provided under these regions with cross-section squareintroduction members (pipes, etc.) 77 a, 77 b projecting downwardtherefrom. The density of the holes H formed in these mouthpieces ispreferably 1 to 5/cm².

Method of Manufacturing a Three-Dimensional Netted Structure

This three-dimensional netted structure 1 is manufactured in thefollowing manner. First, flakes of regenerative PET bottles are heatedand dried for preventing the same from being hydrolyzed, and chemicalsfor finishing the resultant product, or an antibacterial agent and thelike are added suitably in some cases. When filaments come out flat fromthe mouthpiece 34 in the downward direction, the filaments are entangledhelically owing to the entangling actions of the endless members 12, 13of the endless conveyors 14, 15. The filaments start being entangled atthe portions thereof which contact the surfaces of the endless members12, 13 at the entangling-starting time. The density of the portions ofthe filaments which are entangled is high, and that of the portionsthereof which are not entangled is low.

Next, as shown in FIG. 6, a three-dimensional netted structure 1, anobject netted structure is manufactured by extruding a moltenthermoplastic resin downward from a plurality of dies 33, having theextruded filaments of the resin drop naturally to a position between apair of partly submerged endless conveyors 14, 15, and drawing down thefilaments of the resin at a speed lower than the filament droppingspeed. When this netted structure 1 is thus manufactured, the twoendless conveyors 14, 15 are arranged so that a distance between theendless conveyors is set smaller than a width of an assembly of theextruded filaments of the molten resin, and so that both or one surfaceof the assembly of the filaments of the molten resin contacts theendless conveyors 14, 15 before or after these conveyors are submerged.

Both or one of the surface portion of the assembly of the moltenthermoplastic resin drops on the endless conveyors 14, 15, and moves toan inner side of the assembly, so that the surface portion of theassembly becomes dense. Therefore, the percentage of void of the surfaceportion becomes lower than that of a central portion which drops as itis into the water. It is a matter of course that the surface portion inwhich the percentage of void becomes low comes to have an increasednumber of nodes as compared with the central portion having a highpercentage of voids, and that the tensile strength of the surfaceportion becomes noticeably high. The surface portion having a lowpercentage of void comes to have a small area of voids, and forms animpact absorbing layer and a soundproofing layer.

A result showing that a percentage of void of the three-dimensionalnetted structure 1 as a whole high enough to have the netted structurefunction well is in the range of 50% to 98%, though these levels differwith the condition of execution of works on a job site was obtained. Inshort, it is considered that, when the density of the netted structureis high, sounds are blocked. A result showing that, in order to have thethree-dimensional netted structure function as a recycled soundabsorbing building material, a cushioning material, a heat insulatingmaterial and the like, the percentage of void thereof may be setpreferably to not lower than 70% was obtained. In short, when thepercentage of void is lower than 70%, the impact absorbing effect,soundproofing effect, heat insulating effect and cushioningcharacteristics of the netted structure are not in some cases soimproved as was expected. It is recommended that the three-dimensionalnetted structure 1 may be designed suitably with the percentage of voidset in the range of 70% to 98% in accordance with the use of the nettedstructure.

A sound absorbing material and a cushioning material have a preferablepercentage of void of 85 to 98%, an impact absorbing material to beprovided under a floor 40 to 80%, and a collision-preventing impactabsorbing material 60 to 90%. A preferable range of the percentage ofvoid varies with the use of the netted structure.

The percentage of void=100%−{(B÷A)×100%}, wherein A represents a productof the specific gravity of the resin and the volume of thethree-dimensional netted structure; and B represents the weight of thenetted structure.

The thermoplastic resin used in this method is obtained by pulverizingPET bottles into flakes, which are used as a raw material or a main rawmaterial. However, resins including a polymer, such as polypropylene,etc. or a resin obtained by blending a plurality of kinds of polymerstogether, etc. may be used as a main raw material without trouble aslong as the resin can be processed by a regular extrusion moldingmachine.

In the step of forming three-dimensional netted structures to finalmodified shapes, a mechanism for equalizing the inner pressure of thedies, and drawing down an assembly of filaments at two, three or foursurfaces thereof or at an intermediate portion thereof is used. Thisenables such characteristics to be given to this netted structuremanufacturing method that include its capability of attaining anapparent density of a product of 0.02 to 0.9 g/cm³, changing thefilaments of the molten resin from a randomly and helically entangledstate into a state of a flat plate, and turning the surface portions ofthe three-dimensional netted structure including the front, rear, leftend and right end surfaces with respect to the direction of thethickness thereof into flat surfaces and surfaces of modified shapes,i.e., projecting and recessed surfaces. The mouthpiece of a die used toform the three-dimensional netted structure is made so that a nettedstructure of a rod type shape, modified shapes (shape of a pipe and ashape of the letter “Y”), etc. and a netted structure of various othershapes devised by combining these shapes together can be obtained.

The three-dimensional netted structure is subjected to compression bythe rolls of a draw-down machine to obtain a super-dense sheetstructure. The inner pressure of the dies used to have the regeneratedPET resin discharged uniformly from the dies is equalized, and the threeor four surfaces of an assembly of filaments of a molten resin extrudedwhen the three-dimensional netted structure is manufactured is broughtinto contact with the draw-down conveyors by which these surfaces areshaped. In short, the assembly of filaments of the molten regeneratedPET resin is formed at the three or four surfaces thereof to shapes of afinal product. For example, a resin filament assembly is drawn up asnecessary around polygonal conveyors to form a product. In one of themethods of obtaining a three-dimensional netted sheet, filaments of amolten resin are extruded downward from a plurality of dies, and droppednaturally onto water surface or to a position between partly-submergedconveyors. Thus, a randomly and helically entangled filament assembly ismade, which forms a three-dimensional netted sheet.

It was ascertained that, when the speed of the endless conveyors wasvaried, the density of a sheet of 1.0 m in width and 100 mm in thicknessvaried.

It was further ascertained that the density of the sheet varied inaccordance with the variation of a discharge rate of the extruder.

The mouthpiece 34 having about 3500 substantially regularly spaced holesH of 0.5 mm in diameter was fixed to the dies 33 having an area of 1.0m×180 mm in a uniaxial extruder having a screw of 75 mm in diameter. Thewater tank 18 having a water level in a position about 120 mm below thedies 33 is provided, and a pair of endless conveyors 14, 15 of 1.2 m inwidth were installed substantially vertically in the tank with aclearance of 50 mm left therebetween, in such a manner that upperportions of the endless conveyors project upward from the water level byaround 40 mm.

In this apparatus, the molten resin filament assembly was extruded fromthe mouthpiece 34 at an extrusion rate of 120 kg/hr to a positionbetween the endless conveyors 14, 15 so that two surfaces of the moltenresin filament assembly dropped on the endless conveyors, by controllingthe temperature of the dies 33 so that the temperature of the resinbecame 240° C. while plasticizing a regenerated PET resin by heating thesame. During this time, the draw-down speed of the endless conveyors 14,15 was set to 0.7 m/min. The molded product held between the endlessconveyors 14, 15 and moved down changed its direction in a lower portionof the interior of the water tank 18, and was moved from the side of thewater tank which is opposite to the extruder to the water surface. Whenthe molded product came out of the water tank 18, the water thereon wasblown off with compressed air or by a vacuum pump.

The three-dimensional netted structure thus obtained had a width of 1.0m, a thickness of 50 mm, and a density of 0.07 g/cm³ to 0.14 g/cm³. Thisnetted structure may be used as a heat insulating material, a groundmaterial, and a sound absorbing material, and for a drain pipe, etc.

The above-described three-dimensional netted structure 1 and apparatus10 for manufacturing the same netted structure enable a finishingoperation on a later stage to be omitted, the degree of straightness ofsurfaces of the netted structure to be improved, a demand for a nettedstructure having modified shapes to be met, and the durability of thenetted structure to be improved.

Owing to this mode of embodiment, the PET bottles which do not have usesin the existing circumstances newly find a use as materials for athree-dimensional netted structure, and it is considered that a recoverypercentage of the PET bottles will increase. This causes the recyclingof the PET bottles to be greatly promoted.

FIG. 12 shows a modified mode of the apparatus 50 for manufacturing afour-surface-molded three-dimensional netted structure, and FIG. 12A isa drawing corresponding to FIG. 9B and shows a pair of rolls 56, 57 asdescribed above which have a single or a plurality of projections 90 ato 90 c on the respective surfaces thereof (the illustrations of theroll 57 and its projections are omitted). These projections are formedso as to provide recesses in side surfaces of the three-dimensionalnetted structure. Each of the projections 90 a to 90 c has angularportions and an arcuate side portion in cross section. Although therecesses referred to above and formed in the side surfaces of the nettedstructure ought to become rectangular theoretically, the recesses becomecurvilinear since the resin filaments drop into the space between theendless conveyors from above as above-mentioned, causing blind regionsin which the resin filaments do not enter to occur. In short, therecesses become roundish.

FIG. 12B corresponds to FIG. 9C, and shows endless conveyors (theillustrations of the endless conveyor 55 and its projections areomitted) formed by providing a single or a plurality of projections 96on the surfaces of two endless belt conveyors like those of theabove-mentioned belt conveyors 54, 55, etc. This modified apparatus canalso be formed by incorporating cams and springs in the rotary bodies,such as the above-mentioned rolls 56, 57 or endless conveyors 54, 55 sothat the projections are forced out in the outward direction by the camssynchronously with the rotations of the rotary bodies. This enables theoccurrence of blind regions to be reduced, and more precise recesses tobe formed. Since the construction of the other parts is identical withthat of the corresponding parts of the apparatus shown in FIGS. 9B and9C, the illustrations and description of the latter will be utilized andquoted.

The demands for the recycling of the products of the three-dimensionalnetted structures have become diversified, and cannot be met under thepresent circumstances in some cases. For example, when it is desiredthat a mixture of not smaller than two kinds of regenerated resins beutilized, some of these raw materials prove separable during recyclingoperations therefor, and some prove non-separable. Non-separable rawmaterials are sometimes mixed into a starting material, and therecycling and utilizing of raw materials actually become impossible insome cases in spite of the effort made to recycle the materials. Thereare various cases where the same raw material is used for a certainpurpose, which include a case where changing the shape of a product isdesired, such as a case where forming sparse and dense regions isdesired, a case where forming hollow portions on a later stage isdesired and similar cases, or a case where improving the moldability ofthe materials is desired. The below-described embodiment is carried outso as to prevent troubles from occurring in the regeneration of athermoplastic resin, and attain the easiness of changing the shape of aproduct.

A three-dimensional netted structure 101 is a plate typethree-dimensional netted structure, the characteristics of which residein that the netted structure is formed by using a regeneratedthermoplastic resin as a raw material or a main raw material, and has aplurality of filaments helically and randomly entangled and partly andthermally bonded together, as shown in FIG. 13A. This netted structureis made of an inner region 101 a and an outer region 101 b of the sameor different raw materials. A boundary between the inner region 101 aand outer region 101 b is shown by a solid line. The solid line is animaginary line showing the boundary, and the same applies to the othermodes of embodiment which will be described later. It is preferable thatthe densities of two, three or four surface portions of thisthree-dimensional netted structure may be relatively higher than that ofthe portion of the netted structure which is exclusive of these surfaceportions. Namely, the three-dimensional netted structure 101 (refer toFIG. 13A) of this embodiment is two-surface-molded.

This netted structure is molded so that the density of regions thereofwhich extend from the opposite surfaces thereof toward an inner portionthereof by a predetermined distance is high. The density of an innerpart of the central portion thereof is set lower than the mentioneddensity, and the other non-surface-molded surfaces are notstraight-formed. Therefore, it becomes unnecessary that this nettedstructure may be processed on a later stage. In short, a pair ofsurfaces of a large width and one side surface of the netted structureare forcibly molded by endless conveyors which will be described later,and edges of these surfaces are set more esthetically pleasing thanthose of the other surfaces.

A three-dimensional netted structure 102 (refer to FIG. 13B) is athree-surface-molded netted structure, in which all the surfaces exceptthe end surfaces and one side surface are set straight. The regionsextending from all the surfaces of the netted structure except the rightside surface thereof toward an inner portion thereof by a predetermineddistance are molded to a high density. This netted structure is made ofan inner region 102 a and an outer region 102 b of the same or differentraw materials.

A three-dimensional netted structure 103 (refer to FIG. 13C) isfour-surface-molded, in which all the surfaces thereof except an endsurface thereof are set straight. This netted structure is formed bymolding the regions, which extend from the left and right side surfacesof the same netted structure as that of the first mode of embodiment tothe inner part of the central portion thereof by a predetermineddistance, to a high density with the density of the region in the innerpart of the central portion of the netted structure set lower than thementioned density. Namely, the regions extending from all the sidesurfaces of the netted structure toward the inner portion thereof by apredetermined distance are molded to a high density. This nettedstructure is made of an inner region 103 a and an outer region 103 b ofthe same or different raw materials.

A three-dimensional netted structure 104 (refer to FIG. 13D) is athree-dimensional netted structure provided with a single or a pluralityof (one in this embodiment) hollow portions 104 c, and formed for thepurpose of further reducing the cost and for some other purposes. Thisnetted structure is made of an inner region 104 a and an outer region104 b of the same or different raw materials.

A three-dimensional netted structure 105 (refer to FIG. 14A) is formedof three layers of regions 105 a, 105 b and 105 c of the same ordifferent raw materials. The raw materials of all of the three layers ofregions may be different. The raw materials of the regions 105 a, 105 cmay be identical, and that of the region 105 b may be different. The rawmaterials of the three layers of regions may be all identical. Thenetted structure is divided into three layers of regions 105 a, 105 band 105 c in the lengthwise direction thereof.

A three-dimensional netted structure 106 (refer to FIG. 14B) is made oftwo layers of regions 106 a, 106 b of the same or different rawmaterials. The raw material of the two layers of regions 106 a, 106 bmay be different or identical. This netted structure is divided into twolayers of regions 106 a, 106 b in the lateral direction thereof.

A three-dimensional netted structure 107 (refer to FIG. 14C) of asixteenth mode of embodiment is made of two layers of regions 107 a, 107b of the same or different raw materials. The raw materials of the twolayers of regions 107 a, 107 b may be different or identical. Thedirection in which this netted structure is divided into these regionsis that of the thickness of the netted structure unlike the direction inwhich the fourteenth and fifteenth modes of embodiment are divided.

In the embodiment shown in FIG. 3, a high-density sheet 9A (asubstantially non-void-carrying filled region) can be provided partly ina predetermined position in the lateral direction in the embodiment byforming the sheet and the other region by different extrusion moldingmachines through different paths. The description of this embodimentwill be quoted from that given previously with respect to the embodimentof FIG. 3.

Beside these netted structures, netted structures of modifiedcross-section shapes, such as a triangular shape, a shape of the letter“Y”, etc., the illustrations of which are omitted, can also be formed inpractice. As mentioned above, when a raw material is supplied to notsmaller than two regions provided on the mouthpiece, the regulation ofthe manufacturing conditions, such as the temperature of the rawmaterial, extrusion rate of the filaments, etc. can be made easily.

An apparatus 110 for manufacturing a three-dimensional netted structure2 will now be described.

This apparatus 110 for manufacturing a three-dimensional nettedstructure comprises, as shown in FIG. 15, an extrusion molding machine111, a pair of endless conveyors 114, 115 provided with endless members112, 113, a motor 116 for driving the endless members 112, 113, atransmission 117 formed of chains and gears and adapted to change themoving speed of the endless members 112, 113, a water tank 118 forsubmerging parts of the endless conveyors 114, 115 therein, a controlunit 119 and meters, etc.

The description of endless members 112, 113, etc. will be described byquoting that given previously with respect to endless members 12, 13.

As shown in FIG. 15, the extrusion molding machine 111 is formed ofcontainers 131 a, 131 b storing therein the same or different rawthermoplastic resin materials, raw material supply ports 132 a, 132 bprovided at upper portions respectively of the containers 131 a, 131 b,raw material supply pipes 133 a, 133 b connected to the containers 131a, 131 b respectively, a complex die 135 (refer to FIG. 16) connected tothe raw material supply pipes 133 a, 133 b via packings 134 a, 134 b, amouthpiece 136 (refer to FIG. 16) detachably fixable to a lower endportion of the complex die 135, etc. The raw material supply pipe 133 abranches at an intermediate portion thereof into a plurality of (four inthis embodiment) pipe members striding over the raw material supply pipe133 b. The lower end portions of the branches of the raw material supplypipe 133 a are arranged around that of the raw material supply pipe 133b.

As shown in FIGS. 16A and 16B, the complex die 135 has a frame typepartition wall 139 in an inner region of an outer frame 138 so that theinterior of the complex die 135 is divided into two chambers 137 a, 137b, i.e., the complex die is formed so that the same kind of raw materialor two different kinds of raw materials supplied thereto via the rawmaterial supply pipes 133 a, 133 b are not mixed with each other. Evenwhen the raw material supplied through these supply pipes is the same,it is preferable to provide the partition wall 139 for the purpose ofregulating the extrusion rates separately. The particular parts of theinterior of the die of the extrusion molding machine 111 are formed byutilizing the corresponding parts of the first mode of embodiment.Although the raw material supply pipe 133 a is made to branch into fourmembers, the pipe may also be made to branch into a suitable number ofmembers, such as two members (refer to FIG. 17A), three members (referto FIG. 17B), etc.

A mouthpiece 136 has not smaller than two regions so that a raw materialis supplied thereto separately. Therefore, the regulation of theextrusion speed or extrusion rate of filaments is made very easily, andthe moldability of the raw material is improved remarkably. The detailsof a description of the mouthpiece will be given for comparison byquoting the corresponding parts of the description of apparatus 10. Inthis embodiment, a mouthpiece 171 (the area of the region thereof whichis provided with holes H accounts for 90% of a total area of themouthpiece 171) (refer to FIG. 18A) having the holes at substantiallyregular intervals or at suitable intervals is used. In this mouthpiece171, an inner region 171 a and an outer region 171 b are defined by apartition wall 171 c shown by a broken line, and filaments of the sameor different materials are extruded separately and independently fromthese regions correspondingly to raw material supply pipes 133 a, 133 b.

A mouthpiece 172 (refer to FIG. 18B) may also be used, in which an innerregion 172 a and an outer region 172 b which are provided with amultiplicity of holes H are defined by a partition wall 172 c shown by abroken line. The inner region 172 a is formed in a deflected manner withrespect to the outer region 172 b so that the filaments corresponding tothe inner region 172 a are separated easily.

A mouthpiece 173 (refer to FIGS. 18C and 18D) may also be used. An innerregion 173 a and an outer region 173 b which are provided with amultiplicity of holes H are defined by a partition wall 173 c shown by abroken line. The inner region 173 a is held between the pair of outerregion 173 b. In order to form hollow portions in this mouthpiece,regions 173 d, 173 e which do not have holes H are provided in theportions thereof which correspond to the hollow portions, andcross-section square introduction members (pipes and the like) 173 f,173 g extending downward are provided on lower portions of the tworegions.

A mouthpiece 174 (refer to FIG. 19A) may be also used, in which an upperregion 174 a, a central region 174 b and a lower region 174 c which areprovided with a multiplicity of holes H are defined by partition walls174 d, 174 e shown by broken lines to form three stages (three layers)of regions.

A mouthpiece 175 (refer to FIG. 19B) may be also used, in which an upperregion 175 a and a lower region 175 b which are provided with amultiplicity of holes H are defined by a partition wall 175 c shown by abroken line to form two stages (two layers) of regions.

A mouthpiece 176 (refer to FIG. 19C) may be also used, in which a leftregion 176 a and a right region 176 b which are provided with amultiplicity of holes H are defined by a partition wall 176 c shown by abroken line to form two rows (two layers) of regions.

A mouthpiece 177 (refer to FIG. 19D) may be also used, in which a region177 a provided with a multiplicity of holes H, and a slit (linear hole)177 b formed in a suitable portion, such as a central portion, etc. soas to extend parallel to a predetermined direction (lengthwise directionin this example) are defined by partition walls 177 c shown by brokenlines. The slit 177 b exists in a region between the partition walls 177c shown by broken lines. The width, length or position of the slit(linear hole) 177 b can be suitably selected. When a raw material issupplied from the same die to the region 177 a having many holes H andslit (linear hole) 177 b, the wavy form of FIG. 3B is deformed, and themoldability of the material is deteriorated in some cases. However, whenthe above-mentioned mouthpiece 177 is used, the raw material is suppliedfrom not smaller than two kinds of extrusion molding machines 111separately and independently to the holes H of the region 177 a and slit177 b, so that a suitable wavy form is obtained. Instead of the slit 177b, holes H may be provided. In such a case, it is recommended that thedensity of the holes H be set high.

Besides these mouthpieces, mouthpieces of various other specificationscan be used in practice. The density of the holes H formed in theabove-described mouthpieces is preferably set to 1 to 5/cm².

The method of manufacturing a three-dimensional netted structure 1 isutilized.

According to the three-dimensional netted structures 101 to 107, a resindifficult to be separated or a resin impossible to be separated is usedto form the first region 101 a, while a resin possible to be separatedis used to form the second region 101 b, this resin being separatedduring a recycling operation, so that the recycling operation can becarried out repeatedly.

A three-dimensional netted structure divided into regions in accordancewith the properties of the thermoplastic resins can be manufactured, andthe recycling of the thermoplastic resins can be done smoothly. A simpleoperation, such as a region separating operation or some other similaroperation advantageously makes it possible to change the shape of thenetted structure afterward. Since a raw material is supplied to themouthpiece from a plurality of extruders separately and independently,the moldability of the material for the three-dimensional structure isimproved.

An apparatus 210 for manufacturing three-dimensional netted structureaims at providing a method of and an apparatus for manufacturing athree-dimensional netted structure, capable of preventing thedeformation of the endless belts, which causes inconveniences, omittinga finishing operation on a later stage, improving the degree ofstraightness of the surfaces of a netted structure, meeting a demand fora netted structure of modified shapes, and manufacturing a nettedstructure of an improved durability.

The construction of the parts of the apparatus for manufacturing thethree-dimensional netted structure 210 which are different from thecorresponding parts of the apparatuses of other embodiments will bedescribed by utilizing the description of apparatus 10, etc.

The apparatus 210 is formed of an extrusion molding machine 211, a pairof rolls 212, 213 provided in horizontal positions spaced from eachother by a predetermined distance, a pair of rolls 214, 215 (refer toFIG. 20 and FIG. 21) provided below and in alignment with the two rolls212, 213 horizontally so as to be spaced from each other by apredetermined distance, a motor for driving the rolls 212 to 215, atransmission formed of chains and gears and adapted to change the movingspeed of the rolls 212 to 215, a water tank for partly submerging of thetwo rolls 212, 213 and completely submerging the two rolls 214, 215, acontrol unit, meters, etc. Referring to FIG. 20, a structure providedwith three rolls by removing one of the lower rolls may be employed.

The rolls 212, 213 may be formed of cross-section circular rolls 224(refer to FIG. 22A) as well as rolls of modified shapes. Variousmodified modes of rolls are conceivable which include, for example, aroll 225 (refer to FIG. 22B) having a cross-section saw-tooth outercircumference, a roll having continuously formed recesses andprojections, for example, a roll 226 (refer to FIG. 22C) having an outercircumferential surface similar to that of a gear in section, a roll 227(refer to FIG. 22D) having not smaller than one projection 227 a (forexample, a triangular or circular projection) on an outercircumferential surface thereof, a cross-section elliptic roll 228(refer to FIG. 22E), a cross-section triangular or a hand-made ormechanically molded rice-shaped roll 229 (refer to FIG. 22F), across-section polygonal roll, for example, a cross-section octagonalroll 230 (refer to FIG. 22G), etc.

As shown in FIG. 21, the rolls 212 to 215 are provided with drivingshafts 212 a to 215 a respectively. The driving shafts 212 a to 215 aare supported rotatably on the respective bearings, and driven in thedirections of arrows in FIG. 20 by a driving motor via the transmission.

According to the apparatus 210 described above for manufacturing athree-dimensional netted structure, it becomes possible to omit afinishing operation carried out in a later stage, heighten the degree ofstraightness of surfaces of a netted structure, meet a demand forobtaining netted structures of modified shapes and improve thedurability of a netted structure.

A three-dimensional netted structure 401 is a netted structure in whichsparse portions and dense portions are provided. This netted structurecan be applied to, for example, a wall material from which a gardeningcontainer is suspended, a deck on which a gardening container is placed,a blind, a screen, a bamboo blind-like article, a fence, and a gardeningcushioning material applied to a floral decoration and the like.

The sparse and dense portions of the three-dimensional netted structure401 are formed through an operation for regulating a transfer speed ofthe draw-down unit, for example, endless conveyors or rollers, bycontrolling the rotational speed of the motor. This method enables anetted structure having sparse and dense portions stabler than those ofa netted structure manufactured by regulating the liquid pressure of theextrusion molding machine to be obtained.

As shown in FIG. 23A, low-density portions 401 a and high-densityportions 401 b are formed in order and in repetition. In addition, asshown in FIG. 23B, hollow portions 406A, 406B are provided through anetted structure so as to extend in a predetermined direction. Amodified mode of this netted structure may be a gardening cushioningmaterial 402 having a plurality of small through holes 407 a to 407 dextending therethrough in the lengthwise direction as shown in FIG. 23D.The ranges of the density of the sparse portions 401 a and denseportions 401 b can be set suitably. The raw material of thethermoplastic resin, etc. will be described by utilizing the descriptionembodiments described above.

In order to make hollow portions in the netted structure, regions 477 a,477 b not provided with the holes H are formed in the correspondingparts of the mouthpiece 471 as shown in FIG. 24, and downwardlyextending cross-section square introduction members (plate members,pipes, etc.) 477 c, 477 d are provided (refer to FIG. 24B) on lowerportions of these regions. There is another example of the mouthpiecewhich is formed of a mouthpiece 481 (the area of the region thereofwhich is provided with the holes H accounts for 90% of a total area ofthe mouthpiece) (refer to FIG. 24C) in which a predetermined number ofholes H are formed at substantially regular intervals. In order to formhollow portions in the netted structure, this mouthpiece is providedwith regions 487 a to 487 d not provided with the holes H in thecorresponding parts thereof, and downwardly extending cross-sectionsquare introduction members (plate members, pipes, etc.) 488 a to 488 dare provided (refer to FIG. 24D) on lower portions of the mentionedregions. The density of the holes H formed in the mouthpiece ispreferably 1 to 5/cm². Besides these mouthpieces, mouthpieces of variousspecifications can be used in practice.

The three-dimensional netted structure 401 can be used as substitutesfor a wall member from which a gardening container is suspended, a wallmember for a floral decoration, a blind and a fence. For example, asshown in FIG. 25, piles 480 (posts may be used instead) are driven intothe ground and set up, and the resultant piles are thrust into thehollow portions 406A, 406B of the three-dimensional netted structure 401and fixed. The three-dimensional netted structure 401 may be dividedinto a plurality of parts, and dimensional selectivity thereof may besecured by combining the divided netted structures with each other. Asuitable number of hanging baskets 482 provided with hooks 481 are hungon the sparse portions 401 a. The hooks 481 are hung on sparse portions401 a more easily than on dense portions 401 b.

This netted structure can also be utilized as a deck. For example, athree-dimensional netted structure 490 is not provided with hollowportions but it is manufactured in a step similar to the step ofmanufacturing the three-dimensional netted structure 401, so that aculture pot 491, a container 492 and the like can be placed thereon. Thenetted structure 490 can also be applied to a screen, a bambooblind-like article, a fence, a floral decoration, etc. As shown in FIG.26, a three-dimensional netted structure 402 can be utilized as a roof,a screen, and a partition for plants in a median strip of a road. Thenetted structure 402 is formed so that it can be fixed to a structure bya suitable device or by passing connecting members 403, such as strings,rings, pipes and the like through small holes 407 a to 407 c thereof.When this netted structure is utilized as a partition for the plants ina median strip of a road, a glare-proofing effect is displayed withrespect to the light of an automobile.

According to the three-dimensional netted structure 401 described above,it can be applied to a wall member for hanging baskets, a deck, a blind,etc. Moreover, this netted structure reduces the manufacturing cost, andhas durability with respect to the wind and rain and sunlight. Thenetted structure is not rotted, and the flexure thereof does not occur.The netted structure is rarely discolored. This netted structure canemploy various colors, and the coloring of the netted structure can bedone freely, so that the range of the selection of colors expands.Moreover, the netted structure has a very high resiliency, and enables ablinding effect to increase and an outer appearance of different senseof quality to be provided, so that the netted structure is veryconvenient.

The three-dimensional netted structure can also be used as a seedbed forplanting a roof with trees. The netted structure is laid in a hole or arecess formed in a suitable position on a gas-permeable and awater-permeable tile. The culture earth is put in the hole or recess,and tree is planted therein.

The three-dimensional netted structure can also be used as a pavementmaterial by pasting gas-permeable and water-permeable tiles on an uppersurface thereof. Owing to the netted structure, the temperature can bereduced.

A three-dimensional netted structure can also be manufactured thecharacteristics of which reside in that the netted structure is formedby preparing as a raw material or a main raw material a thermoplasticresin containing a brittleness causing element, such as an inorganicsubstance, for example, talc; forming a plurality of helically andrandomly entangled and partly and thermally bonded filaments of the rawmaterial by extrusion molding; and cooling these filaments with aliquid, the brittle fracture of the product becoming able to be effectedby applying an external force thereto.

A three-dimensional netted structure obtained by preparing athermoplastic resin as a raw material or a main raw material; forming aplurality of helically and randomly entangled and partly and thermallybonded filaments of the raw material by extrusion molding; cooling thesefilaments with a liquid, and applying a fire resistant material to theresultant filaments or enclosing the filaments with a nonwoven carbonfiber, or a similar three-dimensional netted structure made of the samethermoplastic resin to which the fire resistant material is added canalso be manufactured. The three-dimensional netted structure enclosedwith a nonwoven cloth of carbon fiber can be provided in the ceiling andwalls.

A three-dimensional netted structure 510 is manufactured by forming athree-dimensional netted structure 501 by using curved plates 582, 583as shown in FIG. 27, instead of using the endless members and rolls. Thecurved plates 582, 583 extend perpendicularly to the surface of thedrawing, and are given at their outer surfaces a slidability by coatingthe same with polytetrafluoroethylene. The curved plates are rectangularin side elevation. The curved plates 582, 583 are arranged so that adistance therebetween decreases from upper portions thereof toward lowerportions thereof. The curved plates 582, 583 may have a fixed structure,or they may be formed so that the density and shape thereof in thelateral and longitudinal directions can be varied by rendering adistance of the curved plates variable as shown by broken lines byreciprocating driving units 590, 591 (for example, fluid pressurecylinders). A curved plate 584 is also provided below the curved plates582, 583, and introduces the netted structure 501 suitably to adownstream side draw-down unit.

INDUSTRIAL APPLICABILITY

Methods of and apparatuses for manufacturing a three-dimensional nettedstructure, capable of omitting a finishing operation in a later stage,heightening the degree of straightness of side surfaces of the nettedstructure, meeting a demand for obtaining netted structure of modifiedshapes, and improving the durability of the netted structure can beprovided, and the value of industrial utilization of these inventions invarious kinds of industries is very large.

1. An apparatus for manufacturing a three-dimensional netted structure,the three-dimensional netted structure comprising a plurality offilaments of resin, the filaments being helically and randomly entangledand thermally bonded together, the apparatus comprising: an extrusionmolding machine comprising a plurality of dies each having a mouthpiecewith a plurality of holes; a pair of endless conveyors provided withendless members; a motor adapted to drive said endless members; and atank adapted to partly submerge said endless conveyors therein.
 2. Theapparatus of claim 1, wherein said endless members comprise each aplurality of metal plate members fixed to a plurality of endless chains,and wherein said endless members are separated from one another by apredetermined width of clearance
 3. The apparatus of claim 2, whereinsaid predetermined width of clearance is about 50 mm.
 4. The apparatusof claim 2, wherein each conveyor comprises exactly two endless chains.5. The apparatus of claim 1, wherein said metal plate members arestainless steel.
 6. The apparatus of claim 1, wherein said pair ofendless conveyors are installed substantially vertically in the tank. 7.The apparatus of claim 1, wherein upper portions of said endlessconveyors are adapted to project by about 40 mm above a liquid level insaid tank.
 8. A method of manufacturing a three-dimensional nettedstructure using the apparatus of claim 1, the three-dimensional nettedstructure comprising a plurality of filaments of resin, the filamentsbeing helically and randomly entangled and thermally bonded together,the method comprising: extruding molten filaments of a thermoplasticresin downward from said dies via said mouthpiece, the extruded moltenfilaments taken together forming an assembly of the extruded moltenfilaments, allowing the molten filaments to drop downward under theforce of gravity at a position between said pair of partly submergedendless conveyors, drawing down said molten filaments at a speed lowerthan the filament dropping speed; helically entangling the moltenfilaments by entangling actions of said endless members, wherein saidfilaments start being entangled at portions thereof which contactsurfaces of said endless members; and cooling the entangled filaments ina liquid in said tank.
 9. The method of claim 8, wherein the distancebetween said endless conveyors is set smaller than the width of theassembly of the extruded filaments, whereby one surface or two surfacesof the assembly of the filaments contact said endless conveyors at aportion of said conveyor that is not submerged.
 10. The method of claim8, wherein the distance between said endless conveyors is set to besmaller than the width of the assembly of the extruded filaments,whereby one surface or two surfaces of the assembly of the filamentscontact said endless conveyors at a portion of said conveyor that issubmerged.
 11. The method of claim 8, wherein after extruding moltenfilaments of the thermoplastic resin, one surface portion or two surfaceportions of the assembly of the molten thermoplastic resin drop on theendless conveyors, and move to an inner side of the assembly, wherebythe surface portion of the assembly becomes dense.
 12. The method ofclaim 8, wherein said mouthpiece further comprises a slit, said slitextending in the lengthwise direction of said mouthpiece, whereby thethree dimensional netted structure additionally comprises asubstantially non-void-carrying sheet which forms a wavy shape thedirection in which the resin is extruded.
 13. The method of claim 8,wherein said mouthpiece has a region not provided with holescorresponding to a hollow portion in the three-dimensional nettedstructure arranged in the direction in which the resin is extruded.